1. Field of the Invention
The present invention generally relates to ventilation of semiconductor manufacturing apparatuses and, more particularly, to a technique for ventilating semiconductor manufacturing apparatuses installed in a clean room.
2. Description of the Related Art
Generally, semiconductor manufacturing apparatuses are installed in a clean room in which temperature and humidity controlled clean air is circulated.
From among the semiconductor manufacturing apparatuses, a process apparatus or a peripheral apparatus, which handles a special gas such as a material gas, is provided with a casing such as a housing or an enclosure so that if gas leakage occurs, the leakage gas cannot spread into the clean room. Conventional semiconductor manufacturing apparatuses of this kind are provided with an air intake port on the casing and an exhaust port for exhausting air in the casing so as to continuously ventilate the interior of the casing by introducing the clean room air into the casing though the air intake port and exhausting the air in the casing from the exhaust port to an exhaust duct, which designed to match the characteristics of the special gas. According to such a structure of the casing and ventilating method, if gas leakage occurs in the apparatus, the leakage gas does not spread outside the casing, and is exhausted to the exhaust duct together with the clean room air, which has been drawn into the casing.
Additionally, semiconductor manufacturing apparatuses, which generate heat during operation, also have the same casing structure as the above-mentioned structure so as to continuously ventilate the interior of the casing by introducing the clean room air into the casing though the air intake port while exhausting the air in the casing from the exhaust port of the casing to a heat exhaust duct. In this case, the heat generated by the apparatus is discharged to the heat exhaust duct according to an air-cooling method using the clean room air as a cooling medium.
As mentioned above, in the conventional semiconductor manufacturing equipment, ventilation is performed by using the clean room air, which is clean and has a controlled temperature and humidity. The clean room air used for ventilation is a clean air that is produced by spending a large cost, and such a costly air is continuously dumped to the exhaust duct just in case of gas leakage and to release heat. Accordingly, in an air conditioning system of a clean room, a large amount of conditioned air must be supplied or replenished by using a large power for transporting air so as to maintain a pressure difference of the clean room, which causes a large load to the air conditioning system.
It is a general object of the present invention to provide an improved and useful ventilating method and ventilating system in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a ventilating system for semiconductor manufacturing apparatuses, which ventilating system can reduce energy consumption with respect to air-conditioning and a power spent for transporting air in a clean room by minimizing an amount of circulating air in a clean room.
Another object of the present invention is to provide a ventilating system for semiconductor manufacturing apparatuses, which ventilating system can reduce a load to special gas exhausting apparatus which treats special gasses handled by the semiconductor manufacturing apparatuses.
A further object of the present invention is to provide a ventilating system for semiconductor manufacturing apparatuses, which ventilating system can prevent gas leakage in a clean room.
In order to achieve the above-mentioned objects, there is provided according to the present invention a method for ventilating a semiconductor manufacturing apparatus installed in a clean room, the method comprising the steps of: introducing clean room air, which is supplied to the clean room, into an air circulating system including the semiconductor manufacturing apparatus, the air circulating system being separated from an atmosphere in the clean room; and circulating the clean room air within the air circulating system.
Additionally, there is provided according to the present invention a ventilating system for ventilating a semiconductor manufacturing apparatus installed in a clean room, the ventilating system comprising: a casing enclosing the semiconductor manufacturing apparatus in a substantially airtight state, the casing having an air intake port and an air exhaust port; and an air circulating system having a fan for circulating air within the air circulating system, an outlet of the fan being connected to the air intake port of the casing of the semiconductor manufacturing apparatus via a first air passage, an inlet of the fan being connected to the air exhaust port of the casing via a second air passage.
According to the present invention, the air for ventilation is supplied in a circulating manner to the casings of the substantially airtight casings of the semiconductor manufacturing apparatus to be ventilated by the air ventilating system that is separated from the atmosphere within the clean room. The air circulating system is provided with a fan, and the air discharged from the outlet of the fan is supplied to the casing of the semiconductor manufacturing apparatus by being passed through the first air passage. The air temporarily remains in the casing, and, thereafter, the air is introduced into the inlet of the fan by being passed through the second air passage so as to be discharged from the outlet of the fan again. Thus, the semiconductor manufacturing apparatus is ventilated within the air ventilating system, which is separated from the atmosphere in the clean room.
In order to effectively release heat generated in the apparatus to be ventilated, the ventilating method of the present invention may preferably control a temperature of the air exhausted from the casing and the temperature controlled air may be supplied to the casing. In order to achieve the temperature control function, the ventilating system of the present invention may preferably comprise a heat exchanger provided to the first air passage or the second air passage so as to control a temperature of the air in the air circulating system.
Additionally, in order to maintain each part of the air circulating system and air in the air circulating system to be clean and continuously maintain the interior of the casing of the apparatus to be ventilated, the ventilating method of the present invention may preferably clean the air discharged from the casing and supply the cleaned air to the casing. In order to achieve the cleaning function, the ventilating system of the present invention may preferably comprise an air cleaning filter provided to the first air passage or the second air passage.
Additionally, in the present invention, a pressure of the air in the air circulating system may be maintained at a constant value or within a predetermined range so as to maintain an amount or a pressure of the ventilating air in the casing. In order to achieve this, the ventilating method of the present invention may preferably discharge the air from the air ventilating system when the pressure of the air in the air circulating system is equal to or higher than an upper limit pressure. In order to achieve the pressure maintaining function, the ventilating system of the present invention may preferably comprise an air release passage and a relief valve provided to the air release passage, the air release passage having a first end and a second end opposite to the first end, the first end connected to one of the first and second air passages, the second end connected to an exhaust duct, the relief valve being opened to release the air in the air circulating system when a pressure in one of the first and second air passages is equal to or higher than the upper limit pressure.
Additionally, the ventilating method of the present invention may preferably comprises the steps of: detecting a pressure in the air circulating system; and replenishing the air circulating system with the clean room air when the pressure in the air circulating system is equal to or lower than a lower limit pressure. The step of replenishing may include the step of introducing the clean room air into the air circulating system until the pressure of the air in the air circulating system exceeds the lower pressure limit.
In order to achieve the above-mentioned pressure maintaining function, the ventilating system of the present invention may preferably comprise: pressure detecting means for detecting a pressure in the first air passage or the second air passage; and air replenishing means for replenishing the air circulating system with air supplied to the clean room when the pressure detected by the pressure detecting means is equal to or lower than the lower limit pressure. Additionally, the air replenishing means may comprise: an air introducing passage having a first end and a second end opposite to the first end, the first end connected to one of the first air passage and the second air passage, the second end being open to an atmosphere within the clean room; an open and close valve provided to the air introducing passage; and controlling means for controlling the open and close valve to open until the pressure detected by the pressure detecting means becomes higher than the lower limit pressure.
In the present invention, a load to the special exhaust apparatus for gas leakage is reduced by circulating the air within the air circulating system without assuming or supposing gas leakage of the apparatuses to be ventilated during a normal time. If gas leakage occurs, necessary safety measures are taken at the time the gas leakage occurs.
For the sake of safety measures when gas leakage occurs, the ventilating method of the present invention may preferably comprise the step of: detecting leakage of a predetermined gas handled by the semiconductor manufacturing apparatus to be ventilated based on the air exiting from the casing within the air circulating system; and discharging the air, which exits from the casing, from the air circulating system to a predetermined external exhaust system when leakage of the predetermined gas is detected. The step of discharging may include the step of diluting the air exiting from the casing by an inert gas.
In order to achieve the above-mentioned safety measure function, the ventilating system of the present invention may preferably comprise: gas detecting means provided to the second air passage for detecting leakage of a predetermined gas in the semiconductor manufacturing apparatus to be ventilated; a switching air passage having a first end and a second end opposite to the first end, the first end connected to the second air passage via a direction switching valve, the second end connected to an emergency exhaust duct; and direction controlling means responsive to a gas leakage detection signal provided by the gas detecting means for controlling the direction switching valve so as to direct the air exiting from the casing to the switching air passage. More preferably, the ventilating system may comprise: an emergency exhaust fan provided to the switching air passage; and fan controlling means responsive to the gas leakage detection signal provided from the gas detecting means for operating the emergency exhaust fan. Further, the ventilating system may preferably comprise: an inert gas supply source supplying an inert gas; an inert gas passage having a first end and a second end opposite to the first end, the first end connected to the inert gas supply passage, the second end connected to the switching air passage; an open and close valve provided to the inert gas passage; and valve control means responsive to the gas leakage detection signal provided by the gas detection means for opening the open and close valve.
It should be noted that the semiconductor manufacturing apparatus in the present invention can be an arbitrary apparatus installed in a clean room for manufacturing a semiconductor device, and includes not only a processing apparatus for applying a predetermined process to a substrate to be processed for manufacturing a semiconductor device but also various peripheral apparatuses relate to the process.
Other objects, features and advantages of the present invention will become more apparent from the scope of the present invention when read in conjunction with the accompanying drawings.